Alloc error handler removed

[HDauven]

Describe the bug
In the latest nightly build (rustc 1.71.0-nightly (f5559e338 2023-04-24) the alloc_error_handler attribute has been removed. handle_alloc_error defautls to panic now for no_std environments.

As a result, the CI breaks and divulges from the nightly specified in the repository itself.

To Reproduce
Either install the specified nightly version and run cargo clippy to observe the problem or see the CI result here.

Additional context
Issues pertaining to the recent changes to alloc_error_handler:

• Reintroduce alloc_error_handler as deprecated
• Stabilize default_alloc_error_handler

We can either opt to lock the CI to the repo version of the nightly Rust version we use, or update the nightly specified in the repo and remove the deprecated allocation error handling for no_std environments.